title: Molecular and biochemical modulation of heat shock protein 20 (Hsp20) gene by temperature stress and hydrogen peroxide (H₂O₂) in the monogonont rotifer, Brachionus sp.
abstract: The monogonont rotifer, Brachionus sp. has been regarded as a potential model for reproductive physiology, evolution, and environmental genomics. To uncover the role of the heat shock protein upon temperature stress and hydrogen peroxide (H₂O₂) exposure, we cloned heat shock protein 20 (Hsp20) and determined its modulatory response under different temperatures and H₂O₂ concentrations. Under different temperature stresses (10 °C and 37 °C), the rotifer Brachionus sp. Hsp20 (Br-Hsp20) gene was highly expressed over time, and reached the maximum level 90 min after exposure, indicating that Br-Hsp20 gene would be involved in the chaperoning process to protect proteins at both low and high temperatures. To test the ability of thermotolerance of the recombinant Br-Hsp20-containing transformed Escherichia coli, we expressed the recombinant Br-Hsp20 protein with 1mM IPTG for 18 h at 30 °C, exposed them at 54 °C with time course (10 to 60 min), and measured cell survival. In this elevated temperature shock (54 °C), the cell survival was significantly higher at the Br-Hsp20 transformed E. coli, compared to the control (vector only). To analyze the modulatory effect of Br-Hsp20 gene on oxidative stress, we initially exposed 0.1 mM H₂O₂ over time and measured antioxidant enzyme activities along with the expression level of Br-Hsp20 mRNA. Upon H₂O₂ exposure, Br-Hsp20 gene was time-dependently upregulated and glutathione peroxidase (GPx), glutathione S-transferase (GST), and glutathione reductase (GR) activities were also elevated at the 12h-exposed group in a dose-dependent manner, indicating that the Br-Hsp20 gene would be an important gene in response to oxidative and temperature stress. Here, we demonstrated the role of the Hsp20 gene in the rotifer, Brachionus sp. providing a better understanding of the ecophysiology at environmental stress in this species.
authors.affiliation: Department of Molecular and Environmental Bioscience, Graduate School, Hanyang University, Seoul 133-791, South Korea.
authors.forename: Jae-Sung
authors.initials: JS
authors.lastname: Rhee
authors.forename: Ryeo-Ok
authors.initials: RO
authors.lastname: Kim
authors.forename: Hee-Gu
authors.initials: HG
authors.lastname: Choi
authors.forename: Jehee
authors.initials: J
authors.lastname: Lee
authors.forename: Young-Mi
authors.initials: YM
authors.lastname: Lee
authors.forename: Jae-Seong
authors.initials: JS
authors.lastname: Lee
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D004926:Escherichia coli / Q000235:genetics; D015870:Gene Expression / Q000187:drug effects; D005978:Glutathione / Q000378:metabolism; D019803:Glutathione Disulfide / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000378:metabolism; D005980:Glutathione Reductase / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D050886:HSP20 Heat-Shock Proteins / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D015801:Helminth Proteins / Q000235:genetics* / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D050296:Microbial Viability / Q000235:genetics; D008969:Molecular Sequence Data; D016877:Oxidants / Q000494:pharmacology; D010802:Phylogeny; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012403:Rotifera / Q000235:genetics* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013312:Stress, Physiological; D013696:Temperature; D014170:Transformation, Genetic
chemical_list: D050886:HSP20 Heat-Shock Proteins; D015801:Helminth Proteins; D016877:Oxidants; D006861:Hydrogen Peroxide; D005979:Glutathione Peroxidase; D005980:Glutathione Reductase; D005982:Glutathione Transferase; D005978:Glutathione; D019803:Glutathione Disulfide